Even the worst zombie movies are clear on one point: a zombie dies when you destroy its head. But a cockroach can live for weeks without its head. How is that possible?

Cockroaches are hardy beasts. They live through urbanization. They live through nuclear war. And it seems they even live through being decapitated. What makes them tougher than zombies, the toughest monsters ever created in movies? Let's start with decapitation.

One of the reasons why decapitation is pretty much always a career-ending injury in humans is the sheer loss of fluids involved. You can't take off someone's head without hacking through some very necessary arteries. The blood loss alone will kill a person. A cockroach doesn't have it so hard. Their equivalent of blood doesn't flow through high-pressure arteries. It seems through their body, and so they don't pump out all their blood and die quickly. They have enough time to seal off the wounds. They also don't breathe through the head and their blood doesn't circulate oxygen.

But of course a zombie doesn't care about that. Why do cockroaches survive when humans drop without their brains? Because cockroaches carry spare brains for just such an emergency. They have ganglia, masses of nerve cells, throughout their body, which allow them to move, stand, and react to touch for weeks after their heads are gone. It's only starvation, dehydration, or infection that kills them. Humans, for all of their advances, have only the one brain. Dummies.

Yes, scientists have determined that cockroaches can live without heads. They also found that heads can live without cockroaches. When scientists decapitated the roaches, they noticed that the heads lived for hours. Because scientists are sick, they noticed that refrigerated heads that were given nutrient solutions lasted even longer.

Will crossing roaches with zombies finally be the thing that wipes us out? Or will it just make a great Syfy movie? You be the judge.